Tag: sysadmin

  • Restore single table from full MySQL database dump

    Restore single table from full MySQL database dump

    Playing with data in databases is sometimes tricky but when you get down to it it’s just couple of lines on the command line. Sometime ago we switched from Piwik PRO to Matomo and of course we wanted to migrate logs. We couldn’t just use the full MySQL / MariaDB database dump and go with…

  • Dockerizing all the things: Running Ansible inside Docker container

    Automating things in software development is more than useful and using Ansible is one way to automate software provisioning, configuration management, and application deployment. Normally you would install Ansible to your control node just like any other application but an alternate strategy is to deploy Ansible inside a standalone Docker image.… Jatka lukemista →

  • Avoiding JVM delays caused by random number generation

    The library used for random number generation in Oracle’s JVM relies on /dev/random by default for UNIX platforms. This can potentially block the WebLogic Server process because on some operating systems /dev/random waits for a certain amount of “noise” to be generated on the host machine before returning a result. Although /dev/random is more secure,…

  • Problems with installing Oracle DB 12c EE, ORA-12547: TNS: lost contact

    Problems with installing Oracle DB 12c EE, ORA-12547: TNS: lost contact

    For development purposes I wanted to install Oracle Database 12c Enterprise Edition to Vagrant box so that I could play with it. It should’ve gone quite straight forwardly but in my case things got complicated although I had Oracle Linux and the pre-requirements fulfilled. Everything went fine until it was time to run the DBCA…

  • Using Let’s Encrypt SSL certificates on Centos 6

    Using Let’s Encrypt SSL certificates on Centos 6

    Let’s Encrypt is now in public beta, meaning, you can get valid, trusted SSL certificates for your domains for free. Free SSL certificates for everyone! As Let’s Encrypt is relatively easy to setup, there’s now no reason not to use HTTPS for your sites. The needed steps are described in the documentation and here’s short…

  • Creating Vagrant Base Box with Veewee

    Creating Vagrant Base Box with Veewee

    Vagrant is a great tool for creating and configuring lightweight, reproducible, portable virtual machine environments but the first step for using Vagrant, downloading an existing “base box”, raises some questions. E.g. How are these unverified boxes built? So, you might end up building your own base box which is often time consuming and cumbersome.… Jatka…

  • Disabling Derby in Oracle WebLogic 12c

    Oracle WebLogic has some interesting traits to help developers frustrate. From Weblogic 10.3.4 and above the Apache Derby Database is included in the installation. That’s fine but from 12.1.2 release it also starts automatically which is usually unwanted, useless and waste of resources. Previous versions of WebLogic didn’t automatically start the Derby database.… Jatka lukemista…

  • Authentication with LDAP provider in WebLogic gets stuck

    Lately we upgraded our Java EE applications to new platform and began seeing stuck threads and slow starting times. The platform was upgraded from OC4J to WebLogic 12c and also the underlying LDAP service was changed to Oracle Access Manager. Looking at the server logs the one possible reason for stuck threads was quite clear:…

  • Weblogic 12c and Managed Server in incompatible state

    Oracle WebLogic application server (WLS) is quite a behemoth and usually works much better than e.g. OC4J which we previously had to use. But sometimes things don’t go as they should and it gets stuck. Some time ago my managed Server was in “FORCE_SHUTTING_DOWN” state and when trying to restart it I got an error…

  • Windows and X11 forwarding with Xming

    Windows and X11 forwarding with Xming

    Usually I prefer to do thing directly from the Linux terminal but sometimes there is a need for remote graphical tools and X11 forwarding. Linux supports X Forwarding with no extra software, on OS X you need e.g. XQuartz and on Windows you need two pieces of software: a secure shell program (ssh) to establish…